Service Manual
64
Service Procedure I:
Thermostat Circuit Testing and Replacement
IMPORTANT NOTE: This procedure
assumes a cool tank.
WARNING
120 volt potential exposure. Use caution making
voltage checks to avoid personal injury.
CAUTION
Use caution to NOT damage connectors when
making voltage measurements or jumping terminals.
Condition: Water heater not operating. Display
shows error code 32 (sensor reading faulty).
Unplug or disconnect electrical power to water heater.
Check continuity of wire harness to sensor. Resistance
of harness should be close to 0 ohms. Replace wire
harness if high resistance is measured (over 0.5
ohms). Check wires for intermittent connections,
shorts, and frayed insulation. Replace if necessary.
If wire harness is O.K., check sensor resistance detailed
in Appendix A: Sensor Resistance At Various
Temperatures at the end of the thermostat testing and
replacement section (pg 64). Replace sensor if needed.
Turn power ON to water heater. Run water heater through
heating cycle and verify proper operation. Sensor
temperature can be viewed when burner shuts off (see
section on viewing the display in Service Mode).
Condition: Water heater not operating. Display shows
error code 65, high water temperature (over 200°F).
Turn power OFF. Draw water to cool tank below 200°F.
Check sensor. Sensor is held in place with a clip
fastened to the well (see photo). Check sensor
wire for potential damage or breaks in the wire
insulation. Is the sensor fully inserted into the well?
WARNING
DO NOT reset the display from the hard lockout state
without correcting the cause of the overheating condition.
Replace sensor clip if damaged.
Replace sensor if damaged.
Check sensor resistance (see
Sensor Resistance Testing).
Continued
on next
page.
N
Y
Checking continuity
of sensor
(disconnected from
control board)
Sensor shown fully
inserted into well
Sensor clip shown
properly installed
64